What I get from this is that you want to have sex with this guy, but you're just not sure if he's ready. I hope that's what you meant, because I'm just going to answer this assumign that's what you meant.
First of all, I'd like to applaud you for considering your boyfriend. So yeah, being someone's first for anything is usually a big deal. It's good that you're considering his feelings.
If you want to suggest this, then just casually bring it up (I can't tell you how to do this exactly because it depends on the situation). When you bring it up, don't think too much about how awkward it's going to be. Just say what's on your mind and your concerns for him (not looking at him or making eye contact with him too much when you say this will help). Ask what he thinks about this, disucss your options, and come up with a decision together. When you talk to him about this, be sure that you guys are alone. I can't stress it enough how much more awkward it will be with other people potentially listening.